It is the Pretérito imperfeito, you’re absolutely right. And we often use it to sound extra polite. The simple present can sound a bit harsh when you’re making a request. And this is actually the same as in English. Many people would rather start a request with “I would like” than with “I want”. This “I would like” bit, in Portuguese, can be translated to the imperfeito “Queria” (verb querer) or to the conditional “Gostaria” (verb gostar). The former is more commonly used.

Good question. The only reason why your logic doesn’t apply is that apetecer is generally considered an impersonal verb. So, in a sentence with apetecer, instead of us being the subject, we are actually the indirect object (and the direct object is the thing we want). That explains why you don’t see “Eu apetece”, but “apetece-me” (Clitic Pronouns: Me & Te ).

“Apeteço-me” exists as well, but it means that you feel like eating yourself! 🙂